System dynamics modeling and prototype investigation of a new SMA-electric motor hybrid linear actuator

This paper presented a new hybrid linear actuator which has significant potential to achieve both large force and large displacement based on SMA wires and DC motors. There were one screw and two locking nuts used to accumulate the small displacements of SMA wire actuators. And the SMA wires were connected in parallel to enhance the force output. A system dynamic model of this hybrid actuator was made on the present study, which was composed by the constitutive model of the SMAs, the electrical and heat transfer behavior of SMA wires, and dynamics of the linear actuation system. Our study explored the accuracy of the model and illustrated the properties of the hybrid linear actuator prototype. Preliminary tests revealed that this kind of hybrid actuator prototype could output a driving force of at least 50N and a single step displacement of 3.34mm in one step cycle. The multi-steps operation frequency under ambient atmosphere was about 0.05Hz. Both numerical simulation and experimental investigation showed that this hybrid linear actuator could achieve large force and large displacement with high stepping accuracy like a step motor.